It is possible that the main title of the report Marfan Syndrome is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.
As Jenny points out, being able to lisp the alphabet song at age two has little to do with 'knowing' the alphabet. And, yes, most children learn the letters by sight and sound in kindergarten, although most are capable of learning this information sooner if diligently taught by parents or others.
13 to 18 Months. What your toddler is doing: As soon as your baby gets out that first word, he'll try for more. Vocabulary builds slowly at first, just a few words a month. Kids seem to prefer nouns at first, then gradually add verbs and adjectives.